Container assemblies consisting of a lid and a container for storing foods under refrigeration by the ordinary consumer are well known of which U.S. Pat. No. 4,471,880 is a typical example. Desirable features in such container assemblies include (a) good sealing integrity at the lid-container junction, (b) the creation of an audible sound at the conclusion of the assembly of the lid to the container so as to inform the user that the container assembly has been properly assembled and thus is in a condition to ensure maximum preservation of the comestible contents, (c) easy assembly of the lid and container, (d) easy disassembly of the lid from the container in both round and, particularly, rectangular container configurations, (e) stable stacking of same size container assemblies one on the other, (f) nesting of same size containers one within another, (g) nesting of a first, and successive if desired, container assemblies, including lids, within a larger container assembly and (h) a gently contoured, pleasing to the eye configuration.
Although a well constructed container assembly having only a single peripheral seal may give acceptable results much of the time, a double seal is highly advantageous since the failure of both seals, and consequent accelerated spoilage of the comestible contents, is highly unlikely. From a probability standpoint, if the failure of a single seal system occurs once in a hundred instances, the total failure of a double seal system would occur only once in ten thousand instances, and possibly even less.
An audible sound, preferably a short click like noise, is desirable when assembling a lid to a container to give the consumer notice that a seal has been made; the consumer, through experience, learns to associate an audible click with a properly assembled container assembly. By the same token, the absence of an audible noise alerts the consumer to the fact that further effort must be made to properly seal the container assembly.
Easy assembly of the lid and the container is also important to consumer acceptance of such container assemblies. Multi-step assembly procedures, or out of the ordinary manipulation of parts, are to be avoided since such steps are not well accepted by ordinary consumers. Most preferably, assembly should be the result of simply placing a lid on a container and pressing, by reasonable hand pressure, once or at most a few times on the lid or about its periphery until the above described audible click is heard. In essence, putting a lid on a refrigerator container should be no more complicated, and should not require any additional mental or physical effort on the part of the consumer, then the assembling of a lid to a container within other container assemblies in the consumer's experience such as large coffee cans, etc.
Easy disassembly is equally important since a container assembly which cannot be easily disassembled becomes a source of irritation and frustration to the consumer and thus may be laid aside as requiring too much effort for today's convenience oriented living styles. A container assembly which is difficult to disassemble also has the potential for spilling the contents thereof as will happen when the consumer tilts such an assembly from the horizontal to obtain more opening leverage, particularly when the container assembly contains liquids, such as soup. Disassembly is especially important in rectangular containers, both square and non-square. The consumer invariably opens a rectangular container from the corner and, in view of the flexibility of the material from which the container assembly is made and the consequent (i) flexing of the lid with respect to the container and (ii) increased tightening of interacting contacting parts on the lid in the container, particularly at the corner areas, a tendency for the lid to grip the container occurs. This gripping makes disassembly a more difficult task with rectangular containers than with round containers.
It is also desirable that such containers be stackable when in use since the height of such containers is generally less than one and a half times the vertical distance between two or more shelves in the refrigerator, and hence refrigerator shelf space is conserved.
Nesting of same size containers is particularly advantageous in utilizing storage areas in locations, such as kitchen cabinets, where such containers are placed when not in use.
Since such containers are frequently sold in sets which may range in size from as little as one half cup up to about three quarts, storage space is also of concern even if the consumer possesses only one container of each capacity. Hence, it is highly desirable that each container in a set of containers, along with its lid, be nestable within the next larger capacity container.
And finally, such container assemblies should, in addition to having all the above described physical and mechanical properties, also have aesthetically pleasing appearance to the eye so that they are readily accepted by the consumer and become items of common place, everyday use. U.S. Pat. No. 4,471,880, though it is said to include an audible click, be easy to assemble and have the capacity to stack in a lid-on condition, totally lacks the feature of double seal which virtually guarantees no spoilage of the contents.